Fuel manufacturing method

ABSTRACT

The objective is to obtain fuel having high combustion calorie and superior handleability from a crude glycerin or a fatty acid mixture that have been discarded as industrial waste products. Disclosed is a fuel comprising a water-insolublized fatty acid substance obtained by water-insolubilizing a fatty acid that is contained in a crude glycerin or fatty acid mixtures that are produced as by-products in the process of producing a biofuel from an animal/plant-derived fat/oil. The water-insolublized fatty acid substance is preferably a water-insoluble fatty acid salt, particularly preferably a salt of a fatty acid with a divalent or trivalent metal ion.

TECHNICAL FIELD

The present invention relates to a fuel, which uses, as a raw material, crude glycerin or a fatty acid mixture produced as a by-product in a process of producing a biofuel from an animal/plant-derived fat/oil, and a method of manufacturing the same.

BACKGROUND ART

A biodiesel fuel (BDF), which uses biomass as a raw material, has attracted great attention in the light of problems such as depletion of fossil fuels and environmental loads due to CO₂ emission in recent years.

The BDF is manufactured by a transesterification reaction between alcohols and animal or plant oils extracted from plants such as soybeans, palm, and maize or animals such as cattle, swine, sheep, and fishes. In the manufacture, a crude glycerin including a fatty acid and a glycerin as main components is produced as a by-product in a large amount, and a majority thereof is wasted without being utilized effectively.

Meanwhile, the crude glycerin has a calorie of about 5,400 kcal/kg, and the fatty acid in the crude glycerin has a calorie of about 8,500 kcal/kg.

The inventors of the present application have focused on this point and made studies on the usability of crude glycerin as a fuel, which is produced as a by-product in the manufacture of BDF using various animal and plant oils as raw materials. As a result, the inventors have found the following and concluded that it is difficult to use crude glycerin directly as a fuel based on the findings.

(1) The crude glycerin has a high pH value due to the effect of an alkali catalyst used in the manufacture of BDF, and thus deteriorates combustion equipment such as a boiler. (2) The crude glycerin generally includes sodium or potassium. Those ionic species may deteriorate combustion equipment. Particularly when sodium coexists with sulfur, sodium sulfate is produced, which further accelerates destruction of an oxide coating film on a metallic surface of combustion equipment by vanadium pentoxide (vanadium attack). (3) Although the combustion of the crude glycerin generates no harmful substance such as dioxin, it is known that it generates soot dust in a large amount. If the amount of the soot dust to be generated cannot be reduced, it is difficult to use the crude glycerin as the fuel. (4) The crude glycerin is a liquid with a high viscosity, hardly replaces any of liquid and solid fuels, and is hard to handle.

-   [PTL 1] JP 2008-023426 A

SUMMARY OF INVENTION Technical Problem

The present invention has been made in the light of the above-mentioned circumstances. An object of the present invention is to provide a fuel excellent in handleability, a fuel excellent in combustion property, a fuel having low harmful effect on combustion equipment during combustion, and/or a fuel capable of producing a high calorie by combustion, from crude glycerin or a fatty acid mixture produced as a by-product in a process of producing a biofuel from an animal/plant-derived fat/oil.

Solution to Problem

The present invention, which solves the above-mentioned problem, is a fuel (claim 1), including a water-insolublized fatty acid substance obtained by water-insolubilizing a fatty acid included in crude glycerin or a fatty acid mixture produced as a by-product in a process of producing a biofuel from an animal/plant-derived fat/oil.

The present invention is characterized in water-insolubilizing the fatty acid in the crude glycerin or the fatty acid mixture. This allows water-soluble components such as glycerin, a sodium ion, and a potassium ion to be separated from the water-insolublized fatty acid substance by washing with water and filtration or centrifugation, for example.

Therefore, by removing glycerin or reducing the amount of glycerin, it is possible to accomplish an improvement in combustibility and an increase in combustion calorie per unit weight. By removing glycerin more completely, the water-insolublized fatty acid substance can be processed into a solid or powder form, which can be used as a solid fuel excellent in handleability.

It is also possible to solve the problem of deterioration of combustion equipment such as a boiler because harmful components such as a sodium ion and a potassium ion are removed or reduced in quantity.

Further, it has been confirmed that the amount of the soot dust generated during combustion can be reduced by removing or reducing the above water-soluble components.

The “animal/plant-derived fat/oil” of the present invention can be any fat or oil that is derived from animal or plant and can be used as the raw materials for producing the biofuel. The animal/plant-derived fat/oil of the present invention includes plant oils such as soybean oil, coconut oil, palm oil, palm kernel oil, corn oil, olive oil, safflower oil, carthamus oil, cotton seed oil, rapeseed oil, castor oil, and sesame oil, animal oils such as lard oil, butter oil, sardine oil, mackerel oil, beef tallow, horse tallow, pork tallow, mutton tallow, and whale oil, and wasted edible oils from restaurants, food factories, and ordinary households, and mixtures thereof.

The “fatty acid mixture” of the present invention refers to a mixture mainly formed of a fatty acid and glycerin produced as by-products in a process of producing a biofuel from an animal/plant-derived fat/oil.

The water-insolublized fatty acid substance in the present invention is preferably produced by coupling the fatty acid to a cation (claim 2), and particularly preferably produced by coupling the fatty acid to a bivalent or trivalent metal ion (claim 3).

That is, a salt of the fatty acid with the bivalent or trivalent ion or the like is poorly soluble in water, and thus, is advantageous in that the water-soluble components can be easily separated by washing with water and filtration, for example. Also, it is possible to reduce the harmful effect on combustion engines when combusted because these salts are not strongly alkaline.

The fuel of the present invention preferably includes the water-insolublized fatty acid substance highly purified by micronizing and/or highly dispersing the water-insolublized fatty acid substance in a suspension having dispersed therein the water-insolublized fatty acid substance using a high pressure dispersion apparatus, and then separating part or all of water and a water-soluble component from the suspension (claim 4). The method of manufacturing a fuel according to the present invention preferably includes: a first step of producing a water-insolublized fatty acid substance by water-insolubilizing a fatty acid included in crude glycerin or a fatty acid mixture produced as a by-product in a process of producing a biofuel from an animal/plant-derived fat/oil; a second step of producing a suspension having dispersed therein the water-insolublized fatty acid substance; a third step of micronizing and/or highly dispersing the water-insolublized fatty acid substance in the suspension using a high pressure dispersion apparatus; and a fourth step of separating part or all of water and a water-soluble component from the water-insolublized fatty acid substance in the suspension after the third step (claim 8).

In such invention, the water-insolublized fatty acid substance in the suspension is micronized and/or highly dispersed using a high pressure dispersion apparatus, and thus, it is possible to incorporate larger parts of water-soluble components such as glycerin, a sodium ion, and a potassium ion contained in the suspension into water. Therefore, the washing with water using a high pressure dispersion apparatus can remove the water-soluble components more efficiently than the washing with water using an ordinary agitator such as a mixer or a stirrer.

The “high pressure dispersion apparatus” in the present invention includes a homogenizer and a nanomizer defined below.

The “homogenizer” refers to an apparatus for micronizing and/or highly dispersing particles by colliding a liquid having dispersed therein the particles, mutually or to a wall surface at a high pressure and/or a high flow rate (a pressure of 30 MPa or more and/or a flow rate of 50 m/sec or more).

The “nanomizer” refers to an apparatus for micronizing and/or highly dispersing particles by cavitation or shearing force when a liquid having dispersed therein the particles is passed through a narrow tube at a high pressure and/or a high flow rate (a pressure of 30 MPa or more and/or a flow rate of 50 m/sec or more). The narrow tube used for the nanomizer may be straight, curved, bended, or branched.

In the present invention, a particle of the water-insolublized fatty acid substance is preferably coated with a film substance (claim 5).

Depending on characteristics and the like of the water-insolublized fatty acid substance obtained by water-insolubilizing the fatty acid, it is not easy in some cases to remove glycerin from the water-insolublized fatty acid substance. It is also not cost-efficient in some cases to remove glycerin by only washing with water and filtration or centrifugation until the water-insolublized fatty acid substance becomes solid or powder.

In such case, the present invention enables to obtain the solid or powder fuel that is mainly formed of the water-insolublized fatty acid substance and is excellent in handleability without increasing the cost significantly by coating the particle of the water-insolublized fatty acid substance containing some glycerin with a film substance to make a microcapsule.

The particle of the water-insolubilized fatty acid coated with the film substance of the present invention can further be made into a pellet or a block in any shape and size using a pelletizer or the like, whereby a solid fuel more excellent in handleability can be obtained.

Further, as the above-mentioned film substance, it is preferred to use an ether derivative of cellulose or an organic acid ester derivative of cellulose. In this case, the ether derivative of cellulose or the organic acid ester derivative of cellulose is a source of a component that acts as a binder. Thus, without additionally adding binder, it is possible to solidify into any size and shape using the pelletizer or the like.

It is not always necessary that all particles of the water-insolublized fatty acid substance are completely coated with the film substance in the present invention. As long as the water-insolublized fatty acid substance can be made into a solid or a powder, the particles of the water-insolublized fatty acid substance may be partially exposed.

BRIEF DESCRIPTION OF DRAWINGS

FIGS. 1(A) and 1(B) are each a diagram illustrating a schematic construction of a nanomizer apparatus.

FIGS. 2(A) and 2(B) are each a diagram illustrating a construction of a generator used in Examples.

FIGS. 3(A) to 3(F) are photographs of appearances of samples prepared in Examples.

FIG. 4 is a diagram illustrating an apparatus used for evaluation of combustibility.

FIGS. 5(A) to 5(C) are photographs of filter papers on which soot dust adhered in evaluation of combustibility.

DESCRIPTION OF EMBODIMENTS

FIG. 1(A) is a diagram illustrating the construction of a nanomizer apparatus 1 used in Examples described below.

The nanomizer apparatus 1 has a housing 2 made from a metal, a holding part 4 that holds a generator 3 that is a main body of the nanomizer apparatus 1 with pressing force from left and right by such as screw fastening, couplers 5 and 6 for connecting to external pipings, and an inlet path 7 and an outlet path 8 for connecting the holding part 4 with the couplers 5 and 6.

A container 9 for retaining a liquid (suspension) to be processed is connected to the coupler 5 on the entrance side of the above-mentioned nanomizer apparatus 1 through a piping 10 to send the liquid pressurized with a high pressure pump 11 into the nanomizer apparatus 1. A piping 12 is connected to the coupler 6 on the exit side to retain the liquid after being processed in a container 13. The container 9 can have a mixer 14 as needed for keeping a suspended state in the suspension.

FIG. 1(B) is a diagram illustrating a generator 3 a with a simple structure that can be used in the nanomizer apparatus 1.

In the generator 3 a, a straight narrow tube 30 having a flow path cross-sectional area S and a flow path length L is formed near its center. The cross-sectional shape of the narrow tube 30 may be any of spherical, elliptic, polygonal shapes, and the like.

In the nanomizer apparatus 1 having such straight narrow tube 30, the particles in the liquid passing through the narrow tube 30 are micronized and/or highly dispersed, for example, by the cavitation generated between the liquid and a tube wall or the shearing force generated by a flow rate difference due to distances from the tube wall.

Values for an aspect ratio R=L/S of the narrow tube 30 are preferably S≦1 mm² and R≧10 mm⁻¹, more preferably S≦0.5 mm² and R≧50 mm⁻¹, particularly preferably S≦0.1 mm² and R≧100 mm⁻¹. The length L of the narrow tube 30 is preferably 2 mm or more, particularly preferably 3 mm or more.

The cross-sectional area S of the narrow tube 30 need not always be constant over the full length. In that case, values for an average cross-sectional area AS (value obtained by dividing an integral value of cross-sectional area of the narrow tube 30 in a lengthwise direction by L) and the aspect ratio R=L/AS are preferably AS≦1 mm² and R≧10 mm⁻¹, more preferably AS≦0.5 mm² and R≧50 mm⁻¹, particularly preferably AS≦0.1 mm² and R≧100 mm⁻¹. A plurality of narrow tubes 30 can also be formed in the generator 3 a.

FIGS. 2(A) and 2(B) are each a diagram illustrating the construction of a generator 3 b used in Examples below.

As illustrated in FIG. 2(A), the generator 3 b has a first flow path element 31, two second flow path elements 32 and 33, and a third flow path element 34.

The first to third flow path elements 31 to 34 are constructed of substrates S1 to S4 that are made of sintered diamond and have substantially square plane shapes and ring members R1 to R4 that are made of a metal and are integrally fitted in their circumference.

The substrate S1 of the first flow path element 31 has two through-holes 31 a and 31 b each having a predetermined radius r1 at positions separated mutually by a predetermined distance D1. The substrates S2 and S3 of the second flow path elements 32 and 33 have long holes 32 a and 33 a each having approximately the same width was r1 and approximately the same length D2 as D1. The substrate S4 of the third flow path element 34 has through-holes 34 a and 34 b each having a radius r2 that is approximately 3 times as large as r1 at positions separated by approximately the same distance as D1. Four pin inserting holes P are formed in a circumferential direction at regular intervals in the ring members R1 to R4 made of a metal of the first to third flow path elements 31 to 33.

FIG. 2(B) illustrates the first to third flow path elements 31 to 34 attached to the holding part 4 of the nanomizer apparatus 1 in a cross-sectional view. The first to third flow path elements 31 to 34 are laminated to be mutually positioned with pins inserted in the pin inserting holes 36 so that the through-holes 31 a and 31 b are communicated with both ends of the long hole 32 a, respectively, the long hole 32 a and the long hole 33 a are communicated at a position intersecting mutually, and the both ends of the long hole 33 a are communicated with the through-holes 34 a and 34 b, respectively.

In the above-mentioned generator 3 b, the four narrow tubes 30 are formed, i.e., (1) the narrow tube 30 having a route that enters from the through-hole 31 a and exits from the through-hole 34 a via the long holes 32 a and 33 a, (2) the narrow tube 30 having a route that enters from the through-hole 31 a and exits from the through-hole 34 b via the long holes 32 a and 33 a, (3) the narrow tube 30 having a route that enters from the through-hole 31 b and exits from the through-hole 34 a via the long holes 32 a and 33 a, and the narrow tube 30 having a route that enters from the through-hole 31 b and exits from the through-hole 34 b via the long holes 32 a and 33 a.

In the above-mentioned generator 3 b, the particles in the liquid are micronized and/or highly dispersed by a similar cavitation or shearing force as in the generator 3 a when the liquid goes straight ahead in the through-holes 31 a, 31 b, 34 a, and 34 b and the long holes 32 a and 33 a. Further, the particles in the liquid are also micronized and/or highly dispersed by impact force or the like when the liquid in the through-holes 31 a and 31 b collides against the surface of the flow path element 33 or the liquids mutually collide at the position at which the long holes 32 a and 33 a are intersected.

A flow path cross-sectional area S and a flow path length L of the narrow tube 30 in the generator 3 b can be set by the thicknesses of the first to third flow path elements 31 to 34, the radii r1 and r2 of the through-holes 31 a, 31 b, 34 a, and 34 b, and width W and the lengths D1 and D2 of the long holes 32 a and 33 a. In Examples below, the generator 3 having a flow path cross-sectional area S of 0.0113 to 0.0133 mm² (internal diameter: 0.12 to 0.13 mmΦ) and a flow path length L of 3.8 mm was used for any of the above-mentioned four narrow tubes 30.

Examples

Crude glycerin produced as a by-product in the manufacturing process of a BDF from wasted edible oils by a transesterification reaction under potassium hydroxide catalysis was obtained from a BDF manufacturer, Sebec Co., Ltd. An experiment of producing a fuel according to the present invention was carried out using this. Crude glycerin obtained from Sebec Co., Ltd. was used as a sample A.

(1) Production of Fatty Acid Magnesium Salt

An aqueous solution of crude glycerin was made by dissolving 20 g of crude glycerin in 100 g of purified water. A fatty acid magnesium salt was precipitated by adding 100 g of a solution of 20% magnesium chloride hexahydride by little and little to the aqueous solution of crude glycerin while stirring with a stirrer. As a result, a dark-brown suspension formed of the precipitated fatty acid magnesium salt, glycerin, potassium ions, water, and the like was obtained.

A dark-brown slurry-like filtration residue (fatty acid magnesium salt slurry) obtained by filtrating this suspension was dried in a thermostat at 105° C. for 2 hours to provide a solid (6.9 g), which was used as a sample B.

The sample B was relatively deep dark-brown and viscous, and seemed to still contain glycerin in a considerable amount. A photograph of the appearance of the sample B is shown in FIG. 3(A).

All of the filtrations in Examples including the above-mentioned filtration were carried out using filter paper (Whatman No. 2, 150 mmΦ).

(2) Removal of Water-Soluble Components

Water-soluble components such as glycerin and potassium ions were removed by washing with water and filtration of the fatty acid magnesium salt slurry produced by the method in the above-mentioned section (1) under the following conditions (a) to (d).

(a) Sample C1 (Washing with Water Using Stirrer Plus Filtration (×1))

A mixture in which 100 g of purified water were added to 23 g of the fatty acid magnesium salt slurry was stirred with a stirrer for 10 minutes and then filtrated. 6.1 g of a solid (fatty acid magnesium salt) obtained by drying 17.5 g of the filtration residue in a thermostat at 105° C. for 2 hours was used as a sample C1.

The sample C1 had much lesser wetness than the sample B, and its dark-brown color was paled out. A photograph of the appearance of the sample C1 is shown in FIG. 3(B).

(b) Sample C2 (Washing with Water Using Stirrer Plus Filtration (×3))

Washing with water and filtration by the same method as in the above-mentioned section (a) were repeated three times. That is, 100 g of purified water were added to 23.3 g of the fatty acid magnesium salt slurry, the mixture was stirred using a stirrer for 10 minutes and then filtrated to yield 18.1 g of a filtration residue. Again, 100 g of purified water were added to this filtration residue, the mixture was stirred using a stirrer for 10 minutes and then filtrated to yield 16.2 g of a filtration residue. Again, 100 g of purified water were added to this filtration residue, the mixture was stirred using a stirrer for 10 minutes and then filtrated to yield 14.8 g of a filtration residue. Then, 5.4 g of a solid (fatty acid magnesium salt) obtained by drying this filtration residue in a thermostat at 105° C. for 2 hours was used as a sample C2.

Both the wetness and the color of the sample C2 were similar to those of the sample C1. A photograph of the appearance of the sample C2 is shown in FIG. 3(C).

(c) Sample C3 (Washing with Water Using Nanomizer Plus One Filtration)

Fatty acid magnesium salt particles in the suspension were micronized or highly dispersed by adding 100 g of purified water to 18.2 g of the fatty acid magnesium salt slurry and passing the suspension through the nanomizer apparatus 1 with a pressure of 100 MPa from a high pressure pump 11. Further, 100 g of purified water were added to this, and the mixture was stirred using a stirrer for 10 minutes and then filtrated to yield 19.7 g of a filtration residue. Then, 5.3 g of a solid (fatty acid magnesium salt) obtained by drying this filtration residue in a thermostat at 105° C. for 2 hours was used as a sample C3.

The sample C3 had lesser wet feeling than the samples C1 and C2, and the color of the sample C3 was paled out as compared to those of the samples C1 and C2. A photograph of the appearance of the sample C3 is shown in FIG. 3(D).

(d) Sample C4 (washing with water using nanomizer plus stirrer plus filtration (×6))

Washing with water and filtration by the same method as in the above-mentioned section (c) were repeated six times. That is, the manipulation in which 100 g of purified water was added to 22.6 g of the fatty acid magnesium salt slurry, the suspension was passed through the nanomizer apparatus 1 with a pressure of 100 MPa, and then 100 g of purified water were added thereto, which was then stirred using a stirrer for 10 minutes followed by filtration was repeated six times. Amounts of the filtration residues obtained by the filtration performed six times were 27.5 g, 22.5 g, 24.3 g, 17.5 g, 20.8 g, and 18.1 g, respectively. Then, 5.0 g of a solid (fatty acid magnesium salt) obtained by drying 18.1 g of the filtration residue obtained by the sixth filtration in a thermostat at 105° C. for 2 hours was used as a sample C4.

The sample C4 had similar wet feeling to the sample C3, and the color of the sample C4 was further paled out as compared with the sample C3. A photograph of the appearance of the sample C4 is shown in FIG. 3(E).

(3) Microcapsulation (Coating with Film Substance)

A fatty acid magnesium salt (20 g) obtained by washing with water using a stirrer and one filtration in the same manner as in the sample C1 (but not being dried at 105° C. for 2 hours) was added to an ethylcellulose solution obtained by dissolving 3 g of ethylcellulose 10 (Wako Pure Chemical Industries Ltd.) in 100 g of methanol (Wako Pure Chemical Industries Ltd., special grade reagent), and an ethylcellulose coating was precipitated on fatty acid magnesium salt particles by dripping 200 mL of purified water at 6 mL/minute in this solution with being stirred using a stirrer. The coated particles were filtrated, and the residue was dried in a thermostat at 105° C. for 6 hours to yield 7.4 g of powder. This powder was used as a sample D.

The sample D was a dried powder having scarce wetness and pale dark-brown color. A photograph of the appearance of the sample D is shown in FIG. 3(F).

(4) Pelletization

The following compositions 1 to 3 were attempted to be pelletized using a pelletizer (PM-350) manufactured by Ueda Tekko K.K. A die temperature of the pelletizer was 54° C. in all cases (the following percentages are represented by weight).

Composition 1: sample D 20%+palm kernel meal 80% Composition 2: sample D 50%+palm kernel meal 50% Composition 3: palm kernel meal 100%

As a result, pellets having sufficient hardness suitable for being used as a solid fuel were able to be molded from any of the compositions 1 to 3.

The pellets molded from the compositions 1 to 3 were used as samples E1 to E3, respectively.

(5) Evaluation of Glycerin Contents

<Measurement Method>

About 3 g of the samples (C1 to C4 and D) were sandwiched with 2 sheets of filter paper (Whatman No. 2, 150 mmΦ)/each of the filter papers was weighed in advance), which was then covered with Saran Wrap and placed under 4.4 kg of a weight thereon for 17 hours. Subsequently, the weight of the filter paper was measured after removing the sample thereon carefully to calculate the amount of glycerin soaked into the filter paper.

<Measurement Results>

The results are shown in Table 1. In Table 1, W1 (g) represents a weighed value of each sample used for the measurement, W2 (g) and W3 (g) represent weighed values of the filter paper (2 sheets) before and after the measurement. The amount of soaked glycerin W4 (g) and a rate of glycerin in each sample R (%) were calculated as W4=W3−W2 and R=W4/W1×100, respectively.

TABLE 1 Sample Sample Sample Sample Sample B C1 C2 C3 C4 Sample D W1 (g) 3.0044 3.0114 2.9837 3.0774 3.0050 3.0777 W2 (g) 2.3830 2.4301 2.4117 2.4236 2.4257 2.4186 W3 (g) 2.5673 2.4467 2.4300 2.4358 2.4377 2.4217 W4 (g) 0.1843 0.0166 0.0183 0.0122 0.0120 0.0031 R (%) 6.134 0.551 0.613 0.396 0.399 0.101

(6) Measurement of Combustion Calorie

<Measurement Method>

Requesting Shimadzu Techno-Research Inc., measurement of combustion calories of the samples A, C2, D, and E1 to E3 was carried out. The measurement was carried out according to JIS-M8814 using a Nenken style automatic bomb calorimeter CA-4AJ manufactured by Shimadzu Corporation.

<Measurement Results>

The combustibility and the combustion calorie per unit weight of each sample measured above were as follows.

Sample A: 5,380 kcal/kg Sample C2: 6,984 kcal/kg Sample D: 6,600 kcal/kg Sample E1: 5,447 kcal/kg Sample E2: 6,020 kcal/kg Sample E3: 4,920 kcal/kg

(7) Evaluation of combustibility

<Evaluation Method>

As illustrated in FIG. 4, an ashtray for measuring an ash content 42, on which about 5 g of a sample 41 had been placed, was set on a tripod mount 43, which was then covered with a transparent glass container 44 with opened top and bottom sides. Filter paper 45 was put on the opened top side 44 a, and a burner 47 was ignited. The soot dust was adsorbed on the filter paper 45 by combusting the sample on the ashtray for measuring the ash content 42 with aspirating from the top side (46 in the figure is a ring-type weight for fixing the filter paper 45).

A combustion state of the sample and a state of generating the soot dust were visually observed, as well as the filter paper 45 on which the soot dust had been adhered by the above-mentioned test was photographed.

<Evaluation Results>

The evaluation was carried out for the samples A, B, and C4.

Photographs of the filter papers 45 after the test for the respective samples are shown in FIG. 5.

The observed combustion state and state of generating the soot dust for each sample are as follows.

Sample A: It was confirmed that the sample A was ignited in a relatively short time after the ignition of the burner 47, but a size and a force of a flame were obviously smaller than those in the samples B and C4. White smoke grew dense during the combustion, the inside of the glass container 44 became unvisible, and observation of the combustion became impossible. As shown in FIG. 5(A), not so much soot dust was adhered on the filter paper 45, but the reason of this is considered that the sample A was not combusted sufficiently. Sample B: The sample was ignited within a few seconds from the ignition of the burner 46, and then continued to combust stably to the end with powerful flame. The relatively dense soot dust was generated during the combustion, and as shown in FIG. 5(B), the filter paper 45 also became black considerably.

Sample C4: The sample was ignited within a few seconds from the ignition of the burner 46, and then continued to combust stably to the end with powerful flame. Although soot dust was generated during the combustion, its generation was much minor compared with the sample B. As shown in FIG. 5(C), the amount of the soot dust adhered onto the filter paper was obviously smaller than in the case of the sample B.

(8) Discussions

The following can be concluded from the results of the above-mentioned evaluations.

[α]Production of Solid Fatty Acid Magnesium Salt

Solid fatty acid magnesium salts (samples C1 to C4) were able to be obtained by adding an aqueous solution of magnesium chloride to liquid crude glycerin (sample A) with a high viscosity, and washing the mixture with water and filtering the mixture.

[b] Glycerin Content

By comparing the content of glycerin in the sample B with those in the samples C1 to C4 in Table 1, it is found that glycerin can be removed effectively by washing the fatty acid magnesium salt with water and filtering the fatty acid magnesium salt.

By comparing the samples C1 and C2 with the samples C3 and C4, it can be concluded that the nanomizer apparatus 1 has the higher effect on removal of glycerin than stirring in the washing with water.

In this regard, however, by comparing the samples C1 and C2, or the samples C3 and C4, it was found that the content of glycerin was not so decreased even if the number of times of the washing with water plus the filtration was increased as long as the same method of washing with water is employed.

It should be noted that, in the evaluation of the glycerin content in Examples above, the glycerin content in each sample was not directly measured, but the calculated glycerin ratios R match the observed results of characteristics and appearances of the respective samples. Thus, it seems that the calculated glycerin content at least faithfully reflects the relative magnitude of glycerin amount in each sample.

[c] Potassium Content

Measurement of potassium ion content in each sample has not been performed because of experiment-schedule-related reasons.

However, the potassium ion is highly soluble in water, and thus the potassium ion content in the samples C1 to C4 and D is considered to be largely reduced by washing with water.

[d] Microcapsulation

The fatty acid magnesium salt of the sample C1 contained glycerin to an extent that the wet feeling was felt to some extent, but dry powder (sample D) was able to be obtained by coating the fatty acid magnesium salt with ethylcellulose.

It should be noted that the glycerin contents in the samples C2 to C4 seem to be equal to or less than that in the sample C1, and thus, when the samples C2 to C4 are used, it is considered to be able to obtain drier (less glycerin leaking) powders.

[e] Pelletization

It was succeeded to pelletize a palm kernel meal blended with 20% or 50% of sample D (samples E1 and E2).

It was also attempted to pelletize a palm kernel meal blended with a larger amount of the sample D, but it was not successful. This is caused by non-elevated temperature of the pellets due to the leakage of an oil component (glycerin). Thus, it is considered to be possible to increase the blending amount of the microcapsulated fatty acid magnesium salt by improving the conditions for the washing with water, the filtration, and the microcapsulation, for example.

[f] Performance as Fuel

Fatty Acid Magnesium Salt

It was confirmed that the sample C2 (fatty acid magnesium salt) had a high combustion calorie (6,984 kcal/kg), which was increased by about 1,600 kcal/kg relative to the sample A (crude glycerin). This seems to be because glycerin having a small combustion calorie was removed.

Although the combustion calories of the samples C1, C3, and C4 were not measured, the glycerin content in these samples was equivalent to that in the sample C2 as shown in Table 1. Thus, it is considered that these samples have high combustion calories equivalent to that of the sample C2.

In the evaluation of the combustibility, it was confirmed that the combustibility in the samples B and C4 (fatty acid magnesium salt) was greatly enhanced relative to the sample A (crude glycerin). This seems to be because the glycerin content in the samples B and C4 is greatly reduced relative to the sample A.

The amounts of the generated soot dust were not able to be appropriately compared between the sample A and the samples B and C4 because the combustibility was largely different between the both. However, the amount of the soot dust from the sample C4 was obviously reduced in the comparison between the samples B and C4. Thus, it was able to be confirmed that the amount of the soot dust was able to be reduced by washing with water.

The samples C1 to C4 have the remaining wet feeling to some extent and have the characteristic that glycerin is leaked with pressure. Thus, their intended use is limited. However, the samples C1 to C4 each have a high combustion calorie and good combustibility as above, can be handled as a solid, and thus, are considered to be able to be used as a solid fuel.

Microcapsulated Fatty Acid Magnesium Salt

The sample D obtained by microcapsulating fatty acid magnesium salt obtained from crude glycerin is dry powder form, has a high combustion calorie (6,600 kcal/kg), and the amount of the soot dust therefrom can be greatly reduced by washing fatty acid magnesium salt with water as above. Although the sample D can have a problem in handleability such as transport because of its powder form, it is considered to be able to be used as a excellent solid fuel depending on intended uses.

Pelletized Fatty Acid Magnesium Salt

The pellets each having a sufficient hardness suitable for the use as a solid fuel (samples E1 and E2) were able to be molded by combining one obtained by microcapsulating the fatty acid magnesium salt obtained from crude glycerin with a palm kernel meal. These samples have a higher combustion calorie (5,447 kcal/kg and 6,020 kcal/kg) than the sample E3 formed of 100% palm kernel meal (4,920 kcal/kg) because of the contained fatty acid magnesium salt and the amount of the soot dust can be greatly reduced by washing the fatty acid magnesium salt with water as above. Thus, these samples are considered to be usable as a excellent solid fuel in various intended uses.

As described above, it was demonstrated that a solid fuel having a excellent performance can be obtained from a water-insolublized fatty acid substance obtained from a crude glycerin.

In Examples above, the case in which the water-insolublized fatty acid substance is the fatty acid magnesium salt was described. However, as long as the fatty acid in crude glycerin is water-insolubilized, glycerin, the sodium ion, the potassium ion, and the like can be separated from the water-insolublized fatty acid substance, and thus, the same effects as Examples above can be accomplished. In particular, a salt of the fatty acid and a bivalent or trivalent metal ion such as calcium or aluminum is poorly soluble in water and weak alkaline, which is a common nature as the fatty acid magnesium salt. Thus, when the water-insolublized fatty acid substance is a fatty acid calcium salt or a fatty acid aluminum salt, the same effects as Examples above can be accomplished. 

1.-8. (canceled)
 9. A method of manufacturing a fuel, comprising: preparing a crude glycerin or a fatty acid mixture produced as a by-product in a process of producing a biofuel from an animal/plant-derived fat/oil; and producing a water-insolublized fatty acid substance by water-insolubilizing a fatty acid included in the crude glycerin or the fatty acid mixture.
 10. A method according to claim 9, wherein the water-insolublized fatty acid substance comprises a water-insoluble fatty acid salt produced by coupling a fatty acid included in the crude glycerin or the fatty acid mixture to a cation.
 11. A method according to claim 10, wherein the cation comprises a bivalent or trivalent metal ion.
 12. A method according to claim 9, further comprising: washing the water-insolublized fatty acid substance with water.
 13. A method according to claim 12, wherein the process of washing the water-insolublized fatty acid substance with water includes: preparing a suspension in which the water-insolublized fatty acid substance is dispersed; and agitating the suspension.
 14. A method according to claim 13, wherein agitating the suspension includes micronizing and/or highly dispersing the water-insolublized fatty acid substance in the suspension with using a high pressure dispersion apparatus.
 15. A method according to claim 13, further comprising separating part or all of water and a water-soluble component from the suspension.
 16. A method according to claim 9, further comprising coating a particle of the water-insolublized fatty acid substance with a film substance.
 17. A method according to claim 16, wherein the film substance comprises an ether derivative of cellulose or an organic acid ester derivative of cellulose.
 18. A method according to claim 9, further comprising solidifying a fuel comprising the water-insolublized fatty acid substance into a defined size and shape through application of a pressure to the fuel alone or a mixture of the fuel with another material. 